1. Field of the Invention
The present invention relates in general to an improved knee prosthesis for replacing at least a portion of a knee joint.
2. Information Disclosure Statement
A knee prosthesis for partially or totally replacing a knee joint which has been damaged due to trauma or disease typically includes a femoral component for attachment to the distal end of a femur, and a tibial component for attachment to the proximal end of a tibia. The tibia component often includes a base or tray for being implanted in the tibia, and an insert or meniscal plate on the face of the tray for articulating with the condyles of the femoral component.
Murray et al., U.S. Pat. No. 4,224,696, issued Sep. 30, 1980, discloses a prosthetic knee including a femoral component for being attached to a femur, a tibial base for being attached to a tibia, and an insert or meniscal plate disposed between the distal plateau or face of the femoral component and the proximal plateau or face of the tibial base. The proximal plateau or face of the tibial component has a concave, compoundly curved surface while the distal face of the insert has a convex surface shaped complementary to the proximal plateau or face of the tibial component so as to permit substantially unrestrained relative sliding motion between the proximal plateau or face of the tibial component and the distal face of the insert when the two are biased against each other.
Brooks et al., U.S. Pat. No. 4,714,474, issued Dec. 22, 1987, discloses a knee joint prosthesis including a tibial component with a base for being attached to a tibia, and a removable articulating surface insert that is locked to the tibial base when implanted.
Lacey, U.S. Pat. No. 4,759,767, issued Jul. 26, 1988, discloses a tibial component of a knee prosthesis that includes a base for being attached to a tibia without bone cement, and a replaceable plateau insert for being non-movably attached to the base by the use of undercut flanges extending upward from the plateau of the base which coact with appropriate grooves in the lower face of the insert.
Jones et al., U.S. Pat. No. 5,071,438, issued Dec. 10, 1991, discloses a prosthetic knee with a tibial prosthesis comprising a baseplate and an articulating surface which pivots on the baseplate about an axis within a medial condylar compartment.
Tuke et al., U.S. Pat. No. 5,219,362, issued Jun. 15, 1993, discloses a knee prosthesis including a femoral component having a medial condyle and a lateral condyle, and a tibial component having a proximal plateau or face with a medial condyle receiving recess and a lateral condyle receiving recess. The medial condyle and medial condyle receiving recess are generally spherical. The lateral condyle receiving recess is in the form of an arcuate groove, and the curvature of the lateral condyle in the sagittal plane is formed about a pair of parallel axes such that as the knee is straightened, the lateral tibial condyle recess is cammed anteriorly, thereby allowing the tibia to rotate medially slightly about its axis as the knee is straightened from a flexed position.
Nothing in the known prior art discloses or suggests the present invention. More specifically, nothing in the known prior art discloses or suggests a knee prosthesis including a tibial component for mounting to the proximal end of the tibia, the tibial component including a proximal surface having a semispherical medial cavity and a lateral cavity; and a femoral component for mounting to the distal end of the femur, the femoral component including a semispherical medial condylar portion for pivotally coacting with the semispherical medial cavity of the tibial component and including a semispherical lateral condylar portion for movably coacting with the lateral cavity of the tibial component; the semispherical medial condylar portion being substantially congruent with the semispherical medial cavity of the tibial component so that substantially complete surface-to-surface contact between the semispherical medial cavity of the tibial component and the semispherical medial condylar portion of the femoral component is provided throughout the range of flexion of the knee joint.